<mat-accordion>
<!-- #docregion basic-panel -->
<!-- #docregion hide-toggle -->
  <mat-expansion-panel hideToggle>
<!-- #enddocregion hide-toggle -->
    <mat-expansion-panel-header>
      <mat-panel-title>
        This is the expansion title
      </mat-panel-title>
      <mat-panel-description>
        This is a summary of the content
      </mat-panel-description>
    </mat-expansion-panel-header>
    <p>This is the primary content of the panel.</p>
  </mat-expansion-panel>
<!-- #enddocregion basic-panel -->
  <mat-expansion-panel (opened)="panelOpenState = true"
                       (closed)="panelOpenState = false">
    <mat-expansion-panel-header>
      <mat-panel-title>
        Self aware panel
      </mat-panel-title>
      <mat-panel-description>
        Currently I am {{panelOpenState ? 'open' : 'closed'}}
      </mat-panel-description>
    </mat-expansion-panel-header>
    <p>I'm visible because I am open</p>
  </mat-expansion-panel>
</mat-accordion>
